The Masters discovered Earth on their stellar travels and decided to colonize it. They sent some Tripods on the planet to study the human race living on the planet. The Tripods were swiftly destroyed by the humans, displaying advanced warfare technology. The Masters decided to take a subtle approach to subjugate the human race.
Through a television show called The Trippy Show, the Masters gradually hypnotized people to become extremely obedient to the Tripods. They then sent more Tripods to Earth to provide the hypnotized people with Caps that would keep them permanently enslaved. Wars between free and capped people were fought, but as the number of the capped grew, the free men lost. The Masters were then free to establish three cities on the planet and rule all of humanity through Caps.
- The White Mountains (Referenced only, first appearance)
- The City of Gold and Lead (Mentioned only)
- The Pool of Fire (Mentioned only)
- When the Tripods Came
- Episode 1: A Village in England: July, 2089 AD (Referenced only)
- Episode 19: Will Is Made a Slave (Mentioned only)
- Episode 20: Hunt for Eloise (Mentioned only)
- Episode 21: The City of Gold (Mentioned only)
- Episode 22: Blessings of the Cognosc (Mentioned only)
- Episode 23: The Cognosc Departs (Mentioned only)
- Episode 24: Escape From the City of Gold (Mentioned only)
- Episode 25: The Forest of Death (Mentioned only)